Advances in the fields of biotechnology and genetic engineering have resulted in the availability of sufficient quantities of biologically active macromolecules such as growth hormones and/or related compounds to make the administration of these agents on a commercial scale economically feasible. Administration of growth hormones and/or related compounds to animals has been reported to provide beneficial effects such as increasing weight gains, increasing milk production in lactating animals, increasing growth rate, increasing feed efficiency, increasing muscle size, decreasing body fat and improving the lean meat to fat ratio.
The above beneficial effects may be accomplished by daily injection or periodic injection of sustained release or prolonged release compositions. Pending Application for United States Letters Patent by S. Cady, R. Fishbein, U. Schroder, H. Erickson, and B. Probasco, Ser. No. 830,158, filed Mar. 20, 1986, and Application for United States Letters Patent of W. Steber, R. Fishbein and S. Cady, Ser. No. 895,608, filed Aug. 11, 1986 and now abandoned, described sustained release compositions utilizing water dispersible carbohydrate polymer-aqueous systems and solid fat and/or wax-oil systems respectively. Prolonged release nonaqueous compositions of polypeptides, preferably associated with metals or metal compounds, and which may additionally contain antihydration agents dispersed in biocompatible oils, are described in European Patent Application No. 85870135.2, published Apr. 4, 1986.
Multiple water-in oil-in water emulsions, represented as W/O/W emulsions, are described as suitable vehicles for the administration of chemotherapeutic agents by L. A. Elson, et al., in Rev. Europ. Etudes Clin. Et Biol., 1970, XV, 87-90 and by J. Benoy et al., in Proceedings of the British Pharmacological Society, Mar. 28 and 29, 1972, 135-136. The use of multiple W/O/W emulsions for oral administration of insulin has been reported by M. Schichiri et al., in Diabetes, Vol. 24, No. 11, 971-976 (1975), and Diabetologia, 10,317-321 (1974).
U.S. Pat. No. 4,083,798 describes pourable multiple W/O/W emulsion compositions which are stabilized by the presence of 1% to 4% on a weight basis of a water soluble protein and 1 to 4% on a weight basis of a gelling polysaccharide in the external aqueous phase. S. Matsumoto et al., Journal of Colloid and Interface Science, Vol. 77, No. 2, 555-563 (1980), describe the effects of osmotic pressure gradients on the water permeability of oil layers in W/O/W multiple emulsions; and A. Abd-Elbary, et al., Pharm. Ind., No. 9, 964-969 (1984) describe the efficacy of different emulsifying agents for preparing multiple emulsions.
It is an object of this invention to provide injectable sustained release compositions of a growth hormone and/or a related compound, wherein the internal aqueous phase contains the growth hormone and/or related compound emulsified in an oil phase which in turn is emulsified in an aqueous phase.